Conversion of hydrocarbon oils



oct 23, 1945.

FRAcTljNA-ron coNENsER A. R. 4GoLDsBY CONVERSION oF amnmocmaor oLs FiledSept. 2', 1942 ARTHUR R.Gol.ossv

4 INVENTCR BY Wy@ om HIS ATTORNEY Patented Oct. 23, 1945 Arthur R.-Goldsby, Beacon, N. Y.,assignor to They York, N. Y., a corporation TexasCompany, New

` of Delaware Application September 2, 1942, Serial No. 456,974

`5 Claims.

This invention relates to the conversion of hy? drocarbonoils and has todo particularly with the cracking of higher `boiling hydrocarbon oilsinto lower boiling products, such. as gasoline.

particularly, the invention comprises a process in which a virgin oil,suc-h as a paramnic stock essentallyfree ofunsaturates, is treated toalter the character of the paraffin hydrocarbon constituents byisomerization or rearrangement of the structure thereof toa form whichis more `desirable in a cracking stock and then the treatedoil-lssubjected to conversion whereby' products of improved antiknockvalue are obtained.

IStocks*essentially free-oi unsaturates and norl mallyproducing aninferior grade or gasoline may' betreated, prior to cracking, withanhydrous ine'-` tallicfhalides whereby straight chain paraffin`h'ydrocarbon constituents 4thereof` areisomerized `to`branch` chainhydrocarbons of substantially the saine boiling range, and the resultingproduct on cra-cking produces a "cracked distillate showing a much"improved `antilmoclf. value;

` "Hydrocarbon oils used as cracking stocks have treated, heretofore,`with metallic` halides butthe treatment has been `suchthatno`apprecableamount'oi' isomerization would be obtained. Thus oilshave-'been treated with metallichalides `to obtain cracking of the oils,under high. ,tem` perajtureswhlch are unsuitable for isomerizaticn. Alsooils to be cracked havebeen mixed at atmostemperatures1 with themetallic halides pre-- limln'ary to the cracking, but the time ofreaction has lnsumcient to obtain isomerization and unsaturatedhydrocarbons have been present inamoiints whicherender the catalystineiiectivc for isomer-ization. l f l l l l For example; it has beenproposed to treat a feed oil, prior to cracking, with an anhydrousaluminum chloride inthe absence of a promoterchamparamn hydrocarbons.One typeof cata lyst which maybe used is the metallic handjes;

Anhydrous aluminmn halides suchas` aluminum bromide and aluminumchloride have been found satisfactory, although other catalystsareintended to be included. The amount of` catalyst used may be about l5to 20% by weight of the oil treated,

although, as indicated later, much higher propon tions may be usedparticolari-yin continuous operations. Thepresence of a hydrogen halideis also desirable, and I prefer to use about 0.5 to 3% of hydrogenchloride or hydrogen bromide, in addi-ition to the aluminum chloride oraluminum bromide. y

The conditions for treatment with the isomerization catalyst may varyconsiderably and will depend on the nature of the oil. Temperatures ofabout 754000K may be used.- The higher temperatures may be used on moreresistant stocks and when it is desired to speed up the reaction.

I prefer, particularly with aluminum chloride, to'

use temperatures of about 20G-275 F. The time will depend on thetemperature, promoter con-- centration, and catalyst to oil ratios,etc.. From a few minutes to several hours may be sufficient. Sufficientpressure is necessary only to keep the material in the liquid phase. Forordinary cracking stocks atmospheric pressure may be used.-

vAt the higher temperatures, considerable gas formation may occur, butthis is largely isobutane which is valuable for use in other processes,such as alkylation, dehydrogenation, etc.

' In the second step the isomerized product is subjected to cracking orreforming. The cracking or reforming opera-tions may be either thermalor catalytic and any well known or preferred method may be used. Ifthermal cracking'- is used, the conventional conditions are about 200-1000 pounds pressure and 'Z50-1100o F. Giood results are obtained atabout 400 pounds and about 900 F. when cracking gas oils. For catalyticVcracking the temperature and pressure conditions. may be somewhat lesssevere. catalysts such as aluminum chloride, sol-id adsorptive catalystsalone or impregnated with various metallic oxides maybe used.Temperatures of about 40`0l000 F. may be used and pressures from 1GO-750pounds. Thermal cracking is ordinarily satisfactory although in somecases catalytic cracking,l particularly with AlCla at about A10ft-700 F.is preferable.

The drawing shows a diagrammatic sketch of one form4 of apparatus forcarrying outthe process of the invention.

Referring to the drawing, the cil to be treated is introduced throughthe line I intoa reaction vessel 2. The catalyst is introduced .throughthe line `3 as a suspension in oil or a hydrocarbon complex. Thecatalyst may be charged as a mixture with the feed oil orl as a solidthrough means other than a line, for'example a. funnel (not shown) Inthe reactor the oil is intimately con.

tacted with the catalyst by a stirrer 5. 'I'he reaction productsare-transferred through the line 6 to a separator'l wherein the catalystis separated from the oil and discharged through the line 8. Thehydrocarbons are passed through the line 9 to an accumulator I0. All ora portion of the normally gaseous hydrocarbons may be released from theaccumulator through the line Il. The liquid products are Withdrawn fromthe bottom of the accumulator through the line I2 by pump I4 and passedthrough the heating coil I5, located in a cracking furnace I6. Thecracked products are discharged through theline I'Iginto an evaporatorI8 wherein vapors and tar are separated. The tar is withdrawn from thebottom of the separator through the line I9.' The vapors are conductedthrough the line 20 to a p le.

in a continuous manner.

an octane number of about 47. On subjecting the treated naphtha tothermal reforming, a gasoline may be obtained having an octane number ofabout 5 to l0 points higher than the gasoline obtained by reforming ltoa similar yield the same naphthaJ which has not received the preliminaryisomerization treatment.

The boiling range of thefeed naphtha may differ from that specified inthe preceding example thus may range froml MCO-450 F., for exam- Y Onthe other hand the feed may be any desired fraction of straight runnaphtha.

Also .the isomerization step may be carried out In continuous operationsthe stream of naphtha hydrocarbons undergoing treatment may be passed,in the presence of fractionator 2| and therein fractionated to separatea recycle stock of higher boiling range than gasoline which may berecycled through the line 22 bythe pump 23 to the coil I5. .Theuncondensed vapors are led from the top of the fractionator through theline 24 and condenser 25. A gasoline condensate is collected iny anaccumulator 26 equip-pedgwith a gas release line 2l and a liquiddraw-off line 28. p

According to one method of operation the isomerization and cracking maybe carried out with the same catalyst or a, mixture of catalystscornprising the isomerization catalyst. K For example the isomerizationmay be carried out at a low temperature with aluminumbromide and thenthe cracking operation conducted at a higher temperature with the samecatalyst. When using aluminum bromideit is sometimes advantageous toseparate at least a portion of the aluminum bromiden for recycling, andadd to the resulting product additional aluminum bromide and thensubject the mixture to cracking conditions. As anvlvexample oftheoperation of the invention, a virgin gas oil charging stock is mixedwith about 10% aluminum bromide. The mixture is agitated for about 40hours at a temperature of about 75 F. in the presence of hydrogenbromide. The aluminum bromide and any sludge is s eparated and thetreated oil subjected to cracking at aboutg875 F. and about 600 pounds.The antiknock value of the gasoline obtained is about 2-5 points higherthan ordinarily obtained without the isomerization treatment.

.As another example ofthe operation of the inv vention, a virgin gas oillis agitated with aluminum chloride for about 2 hours at about 250 F.

in the presence of hydrogen chloride..V The catalyst is separated andthe treated oil subjected to thermal cracking at about 950 F. underabout 400 pounds pressure. The antiknock value of the cracked gasolineisabout 2 to 'points higher than the gasoline produced by similarcracking of the gas oilwhich had notl been givenV the isomerizationtreatment.

While the above examples relate to the cracking of virgin gas oil, it isto b e understood that other oils may be used which are essentially freeof unsaturates. Y

The invention is also applicable to the reforming of straight runnap-htha, in which the naphtha is subjected to isomerization asherein'described prior to subjecting the same to the reforming operation.

For example, a straight run naplitha having a v boiling range of about280 to 400 F. and an octane number of 26 is treated with 20% aluminumchloride and about 0.8% of hydrogen chloride for 3` hours at 260" F. Thetreated naphtha hydrogen chloride, upwardly through an unpacked reactionto-wer filled with a comparatively stationary body of liquid catalyst,the catalyst advantageously comprising a preformed complex of aluminumchloride and hydrocarbon maintained at atemperature in the range aboutto 250 F. and preferably not in-excess of about 300 to 350" F. d

The ratio of liquid catalyst to feed hydrocarbon undergoing treatmentmay range from about 2` to 100 volumes of liquid catalyst'per volume ofnaphtha hydrocarbon within'the tower. It is desirable to'maintain thefeed hydrocarbons in the form of highly dispersed particlesor dropletsduring passage through theV catalyst liquid, the

drop velocity ranging from about. 0.1 to 0.2 or 0.5

ft. per second through the liquid catalyst. l Advantageously, thepreformed liquid complex compound of aluminum chloride and hydrocarbonis of such characterthat whenfa minor portion of complex is mixed withamajor portion of Vwater the heat evolved from the mixture amounts toabout 200 to 400 caloriesper gramof d complex. rIfhe heat of the`mixture is determined by breaking an ampoule containing a weighed amountof complex, i. e., about Sgrams in a weighed quantity of water, i. e.,about 300 grams contained in a'thermos flaskand initially at aboutnormal room temperature. The mixture is stirred and the rise intemperature is measured. TheV heat liberated is calculated as caloriesper gram of complex.

bon atoms per molecule including hydrocarbon compounds which, during thesubsequent reform-Y ing treatment, would form compounds of low octanevalueor else which would be readily decomposed into carbonaceous orother undesirable A material the presence of which wouldl beobjectionable particularly where a catalyst is used in the reformingstep.'V

The resulting isomerized naphtha-is: then sub-j jected to reforming bythermal treatmentat crackingY temperatures inthe range 800 or900 to ,I

1000 F. This reforming treatment may be effected in .the presence of acatalyst and may beeffected with a 4dehydrogenating catalyst inthepresence of hydrogen at temperaturesv in theforegoing temperature range.The reformed naphtha.y

may be subjected to fractionation as already described in connectionwith the method of ow il-v' lustrated in the drawing.

.'Ilhe advantages of the present inventionV api-y pear to be ldue to theformation, in the isomerinaphtha range.

acentos mticnistep; of branched chain i compounds whichon'crackingyieldhighantiknock products. How-` ever,` the inventionis notdependent: onany theory fofreaction, the importantvthing beingl `that byincreasing the branched'l chain `character of the feedlto then-:formingreaction, a substantial imi provementresu-lts in the quality ofthereformed product.;` AI'lieadvantageof increasing the branched chaincharacter of the naphtha `feed priori to reforming 1 by thermaltreatment .is evidenced' further by comparing the quality of gasolineproduce-d by catalytically treating under similar conditions oftemperature a. heavy straight run naphthaand la. more highly` branchedchain naphtha ofsubstantially similar boiling range, `the morehighlybranched chain naphtha being a high boil- `litigifractionsegregated from the product produced byalkylating a low boilingisoparain with normally gaseous olens. The two feed naphthas aree! thefollowing character:

`These two stocks were separately subjected to catalytic cracking in thevapor phase at a temperature of about 850 F. and under a pressure ofabout 35 pounds per square inch gauge, other operating conditions beingmaintained substantially similar in both cases. The cracked product ineach `case was analyzed and found to have Thus, as indicated by theforegoing, the reforming treatment at cracking temperatures of a feednaphtha which is initially of higher branched chain character results inthe produc- Moreover the yield of the light naphtha fraction issubstantially higher.

Accordingly, a modification of the invention involves reforming asynthetic naphtha of highly branched chain character prepared byalkylat- `ing oleiins with parafllns. Normally gaseous ole- `fins andlow boiling normally liquid olens m-ay be reacted with a low boilingisoparafln such as isobutane in the presence of an alkylaton catalystsuch as concentrated sulfuric acid, anhydrous hydrogen fluoride, oraluminum halide-hydrogen halide to produce a product comprising highlybranched chain hydrocarbons boiling within the The high fraction orfractions of this product may be subjected to reforming asl abovedescribed: Residual C4' and lighter Avhydrocarbons from the reformingtreatment, such as olefins and is'oparans may be recycled to thealkylation reaction. Residual and other hydrocarbons may be recycledtothe reforming operau tln. 1 i

A synthetic naphtha also may be made by polymerization with subsequenthydrogenationof the polymernaphtha or any fraction thereof.

i While` mention has been made of isomerizing straight chain hydrocarbonconstituents .of the feed. `nevertheless it is contemplated that otherhydrocarbon constituents of naphtha such as naphthenes also may .beisomerized and then reformed in the subsequent thermal orv catalyticconversion treatment.

Reference has been made previously to effecting isomerization with. apreformed complex of aluminum halide and hydrocarbon. However, thecatalyst may comprise complex formed during continued operation, Complexwill form during the reaction and some complex may be withdrawn from thesystem from time to time. Aluminum halide may be added from time to timefirv continuously in small amount to maintain a. complex catalyst havingthe previously described heatV of hydrolysis characteristic. i

The reforming may be effected in the presence' of dehydrogenatingcatalysts such as chromiaalumina. and molybdena-alumina.`

This application. is a, continuation-impart ofsubjecting straight-runnaphtha, in the substanj tion of reformed naphtha hydrocarbons havingmaterially `greater octane value.

tial absence of unsaturated hydrocarbons, to the action of an aluminumhalide isomerization catalyst in the presence of a small amount ofhydrogen halide at an elevated temperature up to about 275 F. such thatnaphtha hydrocarbons are converted into isomers without substantialformation of hydrocarbons having either an increased or a decreasednumber of carbon atoms per molecule, removing the isomerized naphthahydrocarbon product from further contact with the isomerizationcatalyst, and then subjecting said removed product to reforming byexposing to contact with a cracking catalyst at temperatures in therange 800 to 1000 F. whereby substantial conversion into high antiknockgasoline hydrocarbons is obtained.

2. A process for the manufacture of high antiknock gasoline hydrocarbonswhich comprises subjecting normally liquid naphtha hydrocarbons, in thesubstantial absence of unsaturated hydrocarbons, to the action of analuminum halide isomerization catalyst in the presence of a small amountof hydrogen halide at an elevated temperature up to about 275 F. suchthat substantial conversion of said naphtha hydrocarbons into normallyliquid isomers occurs without substantial formation of hydrocarbonshaving either an increased or a decreased number of carbon atoms permolecule, removing the resulting hydrocarbon product from furthercontact with the isomeriza-V tion catalyst and then subjecting saidremoved product to contact `with a solid adsorptive cracking catalystimpregnated with metallic oxide at a.

temperature in the range of about 800 to 1000 F. whereby substantialconversion into high antiknock gasoline lhydrocarbons is obtained.

3. The process which comprises subjecting a normally liquid saturatednaphtha hydrocarbon in the substantial absence of unsaturatedhydrocarbons to the action 4of an aluminum halide isomerization catalystin the presence of a small amount of hydrogen halide at an elevatedtemperature upv to about 275 F; such that substantial `isomerization tonormally liquid naphtha hydrocarbon occurs Without substantial formationof hydrocarbons having either an increased or a decreased number ofcarbon'atoms per molecule and separately subjecting the resultingisomerized product to reforming by contact with solid adsorptivecracking catalyst at a temperature in the range 800 to 1000 F. wherebysubstantial conversion to isomerized hydrocarbons occurs. y

4; A process for the manufacture of high antiknock gasoline hydrocarbonswhich comprises subjecting straight run naphtha, in the substantialabsence of unsaturated hydrocarbons, to the action of an aluminum halideisomerization catalyst in the presence of a small amount of hydrogenhalide at an elevated temperature up to 'about 275 F. such that naphthahydrocarbons are conasolid adsorptive catalyst containing metallicvertedinto isomers without substantial formation of hydrocarbons havingeithery anincreased or a decreased number of carbon atoms per molecule,removing the isomerized naphtha hydrocarbon product from further contactwith the isomeriza'- tion catalyst and then subjecting said removedproduct to reforming by exposing to contact with a solid adsorptivecatalyst containing metallic' oxide at temperatures in the range'about750 to 1100" F. whereby substantial conversion into high anti-knockgasoline hydrocarbons is obtained.

. 5. Arprocess'for the manufacture of high antiknock gasolinehydrocarbons which comprises.

subjecting straight-run naphtha, inthe substan-v tial absence ofunsaturated hydrocarbons, t0 the action of a metallic halideisomerization catalyst in the presenceof a small amount of hydrogenhalide at an elevated temperature up to about 275 F. such that naphthahydrocarbons are converted into isomers without substantial formation ofhy drocarbons having either an increased or a decreased number of carbonatoms per molecule, removing the isomerized naphtha hydrocarbon productfrom further contact with the isomerization catalyst and then subjectingsaid removed product to reforming by exposing to contact with oxide attemperatures in the range about 750 Vto 1l'00 F. whereby substantialconversion into high anti-knock gasoline hydrocarbons is obtained.-ARTHUR R. GoLDsBY.

